# Phonons#

**Phonons**from the list of possible project types implemented in ASAP.

Then click on the *Parameters* icon to open the Phonon parameters widget.

You can tune the following project parameters:

**Supercell shape**. Supercell size used to calculate the force constant matrix. Check**Symmetric**box to build a symmetric supercell.**Displacement magnitude**. The distance the atoms are displaced to calculate the force constant matrix. Select units between Ang, nm or Borh.

Click on the *Calculator* icon to select the code.

*Run*icon to open the Run widget.

**Run**button to execute the calculation. Please be aware that phonon calculations with SIESTA may take a significant amount of time to complete.

## Phonon workflow: Analysis#

After the Phonon calculation is completed, click on the **Exit and analyse**
button to open the analysis widget.

It is also possible to open the analysis widget by selecting the *Analyse*
icon associated with a completed project,

**Frequency units**.

**Edit band path…**. The widget shows the unit cell Brillouin zone, the band path and the high symmetry

*k*-points.

*k*-points are labelled automatically. The automatic

*k*-point labelling currently supports the following Bravais lattice types:

Primitive cubic

Face-centred cubic (fcc)

Body-centred cubic (bcc)

Primitive tetragonal

Body centred tetragonal

Primitive orthorhombic

The widget also provides the following information:

**Lattice**. Bravais lattice type.**Special points**. The high symmetry*k*-points.**Number of k-points**. The total number of*k*-points that will be used along the whole selected*k*-path.

**Sampling density**to modify the density of the

*k*-points.

**Append point**to add a new

*k*-point to the band path. Then, edit the

*k*-point coordinates and label and add the new label to the path.

**OK**and click on the button

**Replot**to update the figure.

**Density of states**, check

**Plot density of states**box and click on the button

**Replot**.

**Frequency units**.

**Brillouin zone sampling**: Number of*k*-points used to plot the DOS.**Full width at half maximum (FWHM)**: The distance used between the calculated points to perform the smearing.**Smearing**: Gaussian or Lorentzian distribution.